Laura Williams… explained that the clock would be powered by the tides from the Thames.

“There are three giant concentric rings made from recycled glass,” she told me. “Light shines through from the glass in time with the Moon’s cycles so the largest ring shows the lunar phase. Gradually the light waxes on all the way around the ring and connects full circle when it’s full Moon.

“The second ring is like the big hand of the clock. It’s a marker of light that tracks the Moon around the globe so that’s the lunar day cycle.

“The third ring – the smallest – is the small hand that tracks the tide as it goes from high tide to low.”